Interaction of Radiation‐Induced Self‐Interstitials with Vacancy‐Oxygen Related Defects VnO2 (n from 1 to 3) in Silicon

Two stage electron irradiation with thermal heat‐treatments after each stage is used for vacancy‐oxygen‐related defect engineering in Czochralski‐grown silicon (Cz‐Si). The Cz‐Si samples are first irradiated at room temperature with 2.5 MeV electrons and then heat‐treated at 320 °C to anneal out the VO, V2O, and V3O centers and generate the VO2, V2O2, and V3O2 complexes as the dominant vacancy‐oxygen‐related defects. Subsequently, the samples are irradiated at room temperature again and subjected to 30‐min isochronal annealing in the temperature range 75–350 °C. Defect evolution upon the treatments is monitored by means of the local vibrational mode (LVM) absorption spectroscopy. From an analysis of changes in intensity of the LVM lines it is revealed that the second irradiation results in a noticeable decrease in the concentrations of the VO2, V2O2, and V3O2 complexes and an increase in the concentrations of the oxygen dimer and the VO2* defect (metastable state of VO2, which consists of the VO and Oi components). The observed defect transformations are argued to be related to interactions of the radiation‐induced self‐interstitial silicon atoms (I) with the vacancy‐oxygen complexes via the following reactions: VO2 + I → O2i, V3O2 + I → V2O2, V2O2 + I → VO2*. The formation of the VO2* and O2i complexes in Czochralski‐grown silicon is promoted by two stage electron irradiation at room temperature with a heat‐treatment between the stages. The enhanced formation of these defects is caused by the interactions of the radiation‐induced self‐interstitial silicon atoms (I) with the vacancy‐oxygen complexes via the following reactions: VO2 + I → O2i, V3O2 + I → V2O2, V2O2 + I → VO2*.